I am reading upon MGED and how to model inside it with shapes, regions and assemblies.
I found it quite easy once you get the hang of the commands to work in BRL-CAD.
Better familiarity as a user will result in better understanding as a developer. So before diving into the code of MGED I am going through the editor as a user.
Till now I have touched upon basic shapes, regions, assemblies, boolean operations, and raytracing.